If you are having doubts about opening a joint account, I don't want to do it either.
Please tell me if you are having doubts about opening a joint bank account. If you are, I don't want to do it either.
If you are having second thoughts about the joint account, let's forget about it.
「共同名義の銀行口座を開設するのが不安要素になるのなら、私はそれを望まないよ」＝ If you are having doubts about opening a joint account, I don't want to do it either.
他の言い方：
Please tell me if you are having doubts about opening a joint bank account. If you are, I don't want to do it either.
If you are having second thoughts about the joint account, let's forget about it.
共同名義の銀行口座 ＝ joint (bank) account/bank account in both names
不安がある ＝ have doubts about ～/have second thoughts about ～
イギリス 
